Repsol and EADS choose ADEX Control Solutions Powered by NI

Author(s):
Ken Slaven - ADEX S.L.

Industry:
Oil and Gas/ Refining/ Chemicals, Aerospace/Avionics

Products:
CompactDAQ, LabVIEW

The Challenge:
1. - Aerospace; To keep wind speed constant in a wind tunnel during fuselage fire tests 2. - Petrochemical; To provide precise and stable control of temperature, pressure and level in a naphtha splitter column

The Solution:
Applying ADEX adaptive predictive expert controllers inside control and optimization strategy deployed using LabVIEW and Compact FieldPoint.

Background to ADEX Technology

Adaptive Predictive Expert Control ADEX represents a major breakthrough in process control methodology applicable to many industries which require a level of automatic control over processes such as distillation, fermentation, purification, blending and combustion. It is also suitable for high tech applications such as autopilots and advanced navigation for aerospace and naval. This technology is now available within the National Instruments LabVIEW environment. In spite of the enormous advances in industry in general, and the increasing demands of automation and precision, the control technology ‘PID’, which lies at the core, is well out of step with the modern digital age.

ADEX methodology, robust, patented and proven has been designed to bridge this technology gap and help industry to the next level of quality and efficiency.   

 At the core of ADEX is predictive control which anticipates the next steps in continuous processes. When process dynamics change, ADEX adapts automatically and corrects any prediction errors quickly using an adaptive mechanism. When major problems occur where adaptation is not appropriate, an expert module takes over , replicating the actions of an operator to return the process back to normal and adaptive predictive control. This three pronged approach guarantees precise, robust, stable control.

ADEX and National Instruments

ADEX technology available in a National Instruments LabVIEW environment not only includes ADEX controllers at the heart of the system, but also offers a complete application building tool kit benefiting from National Instruments libraries and graphical interface as well as a simulation module for testing strategies. This software package is called ADEX COP (Control and Optimization Platform).  The control application can either be run on PC or connected to a host system via OPC or a compact version can be downloaded onto an NI real time device such as Compact FieldPoint for more direct contact with the process (embedded applications).

Case Histories

 Our presentation shows two examples of such applications:

 1.             Compact Field point: Wind Tunnel application for fire testing (aerospace

 2.             PC based application: Naphtha Splitter Repsol Refinery:

 

 

Case history 1: Wind tunnel EADS /CASA for testing.

 

Challenge: Trying to keep air speed in a wind tunnel constant during tests in spite of adverse conditions such as measurement noise, lack of valve position measurements, pressure auto-regulation of the compressor and hysteresis between the signal to the valve and resulting air speed. These problems made high profile aerospace testing very complicated and uncertain with the existing methods.

 

Solution: Control strategy developed using NI LabVIEW containing ADEX controllers downloaded onto a Compact FieldPoint device. This device was connected to a butterfly valve used to regulate wind speed from a compressor by sending a 4-20mA signal and also to a Pitot tube so that air speed in knots could be calculated based on pressure measured by the tube.

 

Result: The ADEX 1 x 1 controller maintained constant air speed even with all the difficulties listed above and even when the air speed set point was changed from 70 to 100 knots. It proved robust after considerable testing.

 

Conclusion: ADEX NI team work provided the perfect solution in a high tech, aerospace environment, where precise control was required to support the safety issues at stake in the tests.

 

Case history 2: Naphtha Splitter, Repsol Puertollano Refinery

 

Challenge: Existing traditional methods did not provide sufficiently precise and stable control to deliver consistent product quality and throughput.

 

Solution: ADEX controllers inside an ADEX control and optimization strategy programmed in LabVIEW, running on PC and connected to the main Honeywell control system via OPC.

 

Strategy: The quality of separation depended on precise temperature control in the splitter column. This was accomplished by regulating the flow of heating fluid through the reboiler. However, this temperature was very affected by the pressure at the top of the column. To control this pressure, two methods working in conjunction were required. When the

pressure was high, gas could be released from the condenser to flare.

When the pressure was low, nitrogen could be injected into the condenser.

The pressure control was therefore in two parts. Part 1 was based on

opening the valve to flare with the nitrogen injection valve fully closed.

Part two opened the nitrogen injection with the flare valve fully closed.

Each method contributed 50:50 to the total pressure control solution. Finally, the level control was achieved by opening the heavy naphtha outlet valve.

 

Results: To help measure improvement, the standard deviation of the variation of each of the parameters, temperature, pressure and level was used. The improvements, compared with the previous methods were as follows: Temperature 50%, Pressure 80%, Level 15%.

 

Conclusion: The project demonstrated that the power of ADEX could quickly and efficiently be deployed onto a complex chemical industry problem using tools based on NI LabVIEW with ADEX controllers embedded. In this case, the solution ran on a PC connected to Honeywell SCADA system in way which minimized interference with the main SCADA functions while adding considerable value in a key area of process optimization directly impacting the production of a major refinery.

Author Information:
For more information on this Case Study, contact:
Ken Slaven
ADEX S.L.

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